With some 86% of the population its followers, Roman Catholicism is the main faith of Lithuania since the 15th century. It is thus closely associated with Lithuanian culture. While Lithuania has no state religion, the laws generally permit support for religion by public institutions as long as such support is proportional to the number of adherents of those religions in the area. As Catholicism has the most followers almost all over Lithuania, this leads to it enjoying a semi-official status in some cases (for example, the public TV station provides a live coverage of Catholic masses during the key festivals).

Roman Catholicism in Lithuania withstood both the Reformation (16th century) and the church closures under the Russian Empire (19th century). In 1940-1990, Catholicism served among primary forces of defying Soviet occupation and publishing the anti-Soviet “Chronicles of the Catholic Church” that documented the persecution of Lithuanians. As such, the Catholic church has gained an image of the "defender of truth and human freedoms" in Lithuania, which it lacks in the West.

Many small Lithuanian towns or villages are adorned by tall elaborate churches, mostly dating to the early 20h century when the Russian Imperial ban of new Catholic churches was lifted. In other places, older wooden churches (18th – 19th centuries) remain. They are great examples of traditional people’s architecture.

Next to the roads, you may still see some large crosses and small chapels erected by the local people. Lithuanian cross-making is inscribed into UNESCO list of immaterial heritage and the best place to see it is the Hill of Crosses near Šiauliai.

But probably nowhere Roman Catholicism is felt as much as in Vilnius Old Town, where there are many church spires of different periods gone by, from 14th to the 18th century. There are also several miraculous paintings that are visited by pilgrims from far away in Vilnius: the Divine Mercy and the Mary of the Gates of Dawn are the prime examples.

Another famous miraculous painting exists in Šiluva. While the elaborate processions to the holy sites across Lithuanian countryside are less popular today than they were 100 years ago, the religious town holidays are still the main event of the year in many places.

As the Lithuania’s major religion, Roman Catholicism was the prime target of the Soviet anti-religious drive. The Soviets closed many churches and all the monasteries. After independence, most of these buildings have been reopened and repaired but a lack of money means that many others still stand derelict with their priceless artworks destroyed. Although the religious practices were reborn, they are still nowhere as prevalent as they were before the occupation. Only a few percent of Lithuania's Catholics actually go to mass every Sunday (nominally a requirement for the believers).